I need to execute multiple commands using nohup. Each command should be executed after the previous command.

I used this command as an example:

nohup wget $url && wget $url2 > /dev/null 2>&1 &

However that command did not work.

What command should I use for this purpose?

up vote 48 down vote accepted

Wrap it in sh -c:

nohup sh -c 'wget "$0" && wget "$1"' "$url1" "$url2" > /dev/null &
  • 1
    when I launch nohup I get "nohup: ignoring input and redirecting stderr to stdout" so isn't the "2>&1" redundant? – harschware May 14 '14 at 16:38
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    Probably. I think when I wrote the answer I just copied it from the question. – jw013 May 14 '14 at 17:02

Others have already answered about nohup. As a practical side note: I recommend doing this kind of thing within a screen or tmux session. That way you can disconnect, then reconnect later and see the output and final result.

  • 1
    This answer is great for interactive scenarios, but doesn't make sense for scripts or automation. – Jonathan Hartley Jun 13 '16 at 18:09

Wouldn't it be far simpler to create your list of commands in a separate shell file, e.g. command.sh, without any nohup.

Then you call:

nohup bash command.sh

It would be simpler like this:

nohup sh -c "wget $url && wget $url2" > /dev/null 2>&1 &

This however may cause issues if the URLs contain special characters so for a safer option you can use:

nohup sh -c "wget \"$url\" && wget \"$url2\"" > /dev/null 2>&1 &
  • 3
    The only safe way to pass parameters to sh -c is via separate arguments, which can be accessed via the positional parameters ($0, $1, ...). There is no easy or simple way to quote arguments properly for string parsing. Your attempt to use escaped double quotes fails if $url itself contains double quotes. Try a='problem"'; sh -c "echo \"$a\"" yourself and see - you should get a syntax error because sh -c tries to run echo "problem"". – jw013 Sep 5 '12 at 15:57
  • @jw013 Out of interest, does your objection apply equally to the accepted answer by -oh. By you. Presumably not, then. But I don't understand why not! :-) – Jonathan Hartley Jun 13 '16 at 18:12
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    @JonathanHartley I'm not sure I understand your question. If you compare this answer to mine carefully you should notice a difference in the way $url and $url2 are used. – jw013 Jun 13 '16 at 22:50
  • @jw013 Ah, of course. I was being silly. Thank you for setting me straight. – Jonathan Hartley Jun 14 '16 at 16:40

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